All publications cited herein are incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Prior Transcatheter Valve Therapies
Valvular heart disease is characterized by damage to or a defect in one of the four heart valves: the mitral, aortic, tricuspid or pulmonary. The mitral and tricuspid valves control the flow of blood between the atria and the ventricles (the upper and lower chambers of the heart). The pulmonary valve controls the blood flow from the heart to the lungs, and the aortic valve governs blood flow between the heart and the aorta, and thereby to the blood vessels in the rest of the body. The mitral and aortic valves are the ones most frequently affected by valvular heart disease. Transcatheter valve therapies are one treatment option for patients. For example, transcatheter aortic valve replacement (TAVR, also known as TAVI or transcatheter aortic valve implantation) is a procedure for select patients with severe symptomatic aortic stenosis (narrowing of the aortic valve opening) who are not candidates for traditional open chest surgery or are high-risk operable candidates. A replacement valve is inserted percutaneously using a catheter and implanted in the orifice of the native aortic valve. Replacement valves may be artificial (prosthetic valves) or made from animal tissue (bioprosthetic valves). The type of replacement valve selected depends on the patient's age, condition, and the specific valve affected.
Optimal orientation of X-ray fluoroscopic imaging is fundamental to the success of TAVR. An aortic valve has three leaflets: the right coronary leaflet, the left coronary leaflet, and the non-coronary leaflet. During a TAVR procedure, a conventional pigtail catheter is normally oriented in the non-coronary leaflet and used to inject a contrast dye for X-ray imaging. Since dye injection through the pigtail catheter takes place only in the non-coronary leaflet, the other two leaflets depend on dye spilling back and over to be imaged. Hence, this imaging method is unreliable, and may require multiple injections and large amount of contrast dye for completely visualizing the aortic root and determining the co-axial plane of radiographic projection. This imaging method is sometimes supplemented with pre-procedural imaging such as CT scanning Reducing the amount of contrast dye used is of particular benefit to patients on certain drugs or with one or more pre-existing medical condition, such as diabetes, heart failure or reduced kidney function. Such patients are at a greater risk of prolonged or permanent damage from the dye, often resulting in the need for further medical attention or dialysis. A focused and more precise delivery of contrast may also limit the patient's exposure to radiation.
Another challenging step during a TAVR procedure is to advance an instrument (e.g., a guidewire, a catheter, and/or a pressure sensor) across the aortic valve retrogradely from the aorta to the left ventricle. This step of retrograde crossing is usually performed with a curved catheter (for example, an AL1, AL2 or JR4 catheter) and a straight wire, and sometimes requires considerable manipulation, especially for an aortic valve with a high level of stenosis. Accordingly, a need exists for an improved system for efficiently orienting a catheter system with respect to internal vessel and cardiac structures and additionally for imaging internal vessel and valve structures, for example, the aortic valve.